Transparent substrate comprising an antiglare coating

ABSTRACT

A transparent substrate including an antireflection coating, made from a stack of thin layers of dielectric material having alternately high and low refractive indices. This stack includes a high-index first layer having a refractive index n, of between 1.8 and 2.2 and a geometrical thickness e 1  of between 5 and 50 nm, a low-index second layer having a refractive index n 2  of between 1.35 and 1.65 and a geometrical thickness e 2  of between 5 and 50 nm, a high-index third layer having a refractive index n 3  of between 1.8 and 2.2 and a geometrical thickness e 3  of between 70 and 120 nm, and a low-index fourth layer having a refractive index n 4  of between 1.35 and 1:65 and a geometrical thickness e 4  of at least 80 nm.

The invention relates to a transparent substrate, especially made ofglass, intended to be incorporated into glazing and provided, on atleast one of its faces, with an antireflection coating.

An antireflection coating usually consists of a stack of interferentialthin layers, generally an alternation of layers based on a dielectricmaterial having high and low refractive indices. The purpose of such acoating, deposited on a transparent substrate, is to reduce its lightreflection, and therefore to increase its light transmission. Asubstrate coated in this way therefore has its transmittedlight/reflected light ratio increased, thereby improving the visibilityof objects placed behind it. When it is desired to achieve the maximumantireflection effect, it is then preferable to provide both faces ofthe substrate with this type of coating.

There are many applications of this type of product: it may serve forglazing in buildings, for example as a shop display cabinet and asarchitectural curved glass, so as to more clearly distinguish what isdisplayed in the window, even when the internal lighting is low comparedwith the external lighting. It may also serve as glass for a counter.

An application in the fitting-out of vehicles has also been envisaged,especially for cars and trains. Giving a windscreen an antireflectioneffect is particularly advantageous on several counts: it can increasethe light transmission into the passenger compartment, and thereforeincrease the visual comfort of the passengers. It also makes it possibleto eliminate the undesirable reflections which annoy the driver,particularly reflections of the dashboard.

Examples of antireflection coatings are described in patents EP 0 728712 and WO 97/43224.

However, whether referring to display cabinets, counter glass orwindscreens, the glazing involved, once fitted, is not necessarily in avertical position unlike conventional glazing in buildings, for examplecurtain walling. Windscreens are usually inclined at about 60°, whileshop windows and counters are often curved with variable angles ofobservation.

Now, most antireflection coatings developed hitherto have been optimizedto minimize light reflection at normal incidence, without taking intoaccount the optical appearance of the glazing viewed obliquely. Thus, itis known that at normal incidence it is possible to obtain very lowlight reflection values R_(L) with stacks consisting of four layers witha high-index layer/low-index layer/high-index layer/low-index layeralternation. The high-index layers are generally made of TiO₂, whichactually has a very high index of about 2.45, and the low-index layersare usually made of SiO₂. The optical thicknesses of the layers (theirgeometrical thickness multiplied by their refractive index) areexpressed successively in the following manner:(e1+e2)<□/4−e3≧λ/2−e4=λ/4, where λ is the wavelength averaged over thevisible range around 500 nm and e1 to e4 are the thicknesses of the fourlayers deposited in succession on the substrate. The coating may alsocomprise a three-layer stack. In this case, it is preferable that theoptical thicknesses e'1, e'2 and e'3 of the layers in the order in whichthey are deposited on the substrate satisfy the following conditions:□/4−□/2−□/4.

However, the appearance in reflection, especially the intensity of thelight reflection, is not satisfactory when the viewing angle movesslightly away from perpendicular to the glazing.

Studies have been conducted in order to take into account an obliqueviewing angle, but these have not been completely satisfactory either:mention may be made, for example, of patent EP-0 515 847 which proposesa two-layer stack of the TiO₂+SiO₂/SiO₂ type or a three-layer stack ofthe TiO₂+SiO₂/TiO₂/SiO₂ type deposited by sol-gel, but this stack is notas efficient.

The object of the invention is therefore to remedy the abovementioneddrawbacks, by seeking to develop an antireflection coating which canreduce the level of light reflection from a transparent substrate of theglass type over a wider angle-of-incidence range, and more particularlyat an oblique angle of incidence ranging from 50 to 70° with respect tothe vertical, and this being achieved without compromising the economicand/or industrial feasibility of its manufacture. Secondarily, thesubject of the invention is the development of such a coating which isfurthermore capable of withstanding heat treatments, especially if thecarrier substrate is a glass which, in its final application, must beannealed, bent or toughened.

The subject of the invention is first of all a transparent substrate,especially made of glass, comprising, on at least one of its faces, anantireflection coating consisting of thin layers of dielectric materialhaving alternately high and low refractive indices, especially creatingan antireflection effect at oblique incidence, the said substrate beingdefined as follows. It comprises, in succession:

-   -   a high-index first layer 1, having a refractive index n₁ of        between 1.8 and 2.2 and having a geometrical thickness e₁ of        between 5 and 50 nm;    -   a low-index second layer 2, having a refractive index n₂ of        between 1.35 and 1.65 and a geometrical thickness e₂ of between        5 and 50 nm;    -   a high-index third layer 3, having a refractive index n₃ of        between 1.8 and 2.2 and a geometrical thickness e₃ of between 70        and 120 nm;    -   a low-index fourth layer 4, having a refractive index n₄ of        between 1.35 and 1.65 and a geometrical thickness e₄ of at least        80 nm.

Within the meaning of the invention, the term “layer” is understood tomean either a single layer or a superposition of layers in which each ofthem complies with the refractive index indicated and in which the sumof their geometrical thicknesses again remains equal to the valueindicated for the layer in question.

Within the meaning of the invention, the layers are made of a dielectricmaterial, especially of the oxide or nitride type, as will be explainedin detail below. However, this does not exclude at least one of thembeing modified so as to be at least slightly conducting, for example bydoping it with a metal oxide, so as, for example, to also give theantireflection stack an antistatic function.

The invention preferably applies to glass substrates, but it alsoapplies to transparent substrates based on a polymer, for examplepolycarbonate.

The invention therefore relates to an antireflection stack of thefour-layer type. This is a good compromise as the number of layers islarge enough for their interferential interaction to make it possible toachieve a large antireflection effect. However, this number remainssufficiently reasonable for the product to be able to be manufactured ona large scale, on an industrial line, on large substrates.

The thickness and refractive-index criteria adopted in the inventionmake it possible to obtain an antireflection effect over a broad band oflow light reflection, even at high angles of incidence such as 50 to70°, something which is exceptional (this does not prevent, of course,the antireflection stacks of the invention from also reducing the lightreflection at normal incidence).

It has proved difficult to select these criteria, since the inventorshave taken into account the industrial feasibility of the product andthe appearance in light reflection at two levels: both wishing tominimize the value of the light reflection R_(L) at oblique incidenceitself but also wishing to obtain, for this oblique light reflection, asatisfactory calorimetric response, that is to say a colour inreflection whose tint and intensity are acceptable from the aestheticstandpoint.

The inventors have succeeded in this, especially by lowering the valueof R_(L) by at least 3 or 4% between 50° and 70° under illuminant D₆₅,and preferably obtaining negative values of a* and b* in the (L, a*, b*)colorimetry system for this same light reflection. This results in asignificant reduction in reflections and a colour in the blue-greens inreflection, which is currently judged to be aesthetically attractive inmany applications, especially in the automobile industry.

Perhaps the two most striking characteristics of the invention are thefollowing:

-   -   firstly, compared with a standard four-layer antireflection        coating, the thickness of the last, low-index, layer has been        significantly increased: its preferred thickness is greater than        the value of λ4 normally used;    -   secondly, it has been discovered that, unlike the choice usually        made for the high-index layers, it was unnecessary, and even        disadvantageous, to choose materials having a very high index,        such as TiO₂. On the contrary, for these layers it has proved        more judicious to use materials having a more moderate        refractive index, especially of at most 2.2. This therefore goes        counter to the known teaching on antireflection stacks in        general.

The inventors have thus exploited the fact that, at oblique incidence,the low-reflection spectrum broadens and that it is thus possible to beable to use materials whose index is around 2, such as tin oxide SnO₂ orsilicon nitride Si₃N₄. Especially as compared with TiO₂, these materialshave the advantage of being able to be deposited at much higher rateswhen the deposition technique called sputtering is used. Within thismoderate range of indices, there is also a greater choice of materialsthat can be deposited by sputtering, which offers greater flexibility inindustrial manufacture and more options for adding furtherfunctionalities to the stack, as will be explained in detail below.

These “moderate”-index materials also offer greater flexibility from thestrictly optical standpoint: it has been discovered that they allowfiner adjustment of the “pair” of values defining most specifically thelight reflection (layer side) from the substrate, namely on the one handthe light reflection value R_(L) and, on the other hand, the a* and b*values corresponding to it at oblique incidence (as will become apparentfrom the detailed examples below; it is in fact possible to favour oneor other of these two values depending on the intended objective orapplication more).

They also enable the stack to be made overall optically less sensitive,especially from the calorimetric standpoint, to the thickness variationsof the layers in the stack and to the variations in the angles ofincidence at which the glasses are observed.

Given below are the preferred ranges of the geometrical thicknesses andof the indices of the four layers of the stack according to theinvention:

-   -   a for the first and/or third layer, those with a high index:        -   n₁ and/or n₃ are advantageously between 1.85 and 2.15,            especially between 1.90 and 2.10,        -   e₁ is advantageously between 5 and 50 nm, especially between            10 and 30 nm or between 15 and 25 nm,        -   e₃ is advantageously less than or equal to 120 nm or less            than or equal to 110 nm, and is especially at least 75 nm;    -   the second and/or fourth layer, those with a low index:    -   n₂ and/or n₄ are advantageously between 1.35 (or 1.40) and 1.55,    -   e₂ is advantageously between 5 and 50 nm, and is especially less        than or equal to 35 nm or less than or equal to 30 nm,        especially being between 10 and 35 nm,    -   e₄ is advantageously greater than or equal to 90 or 80 nm, and        is especially less than or equal to 120 or 110 nm.

According to an alternative embodiment of the invention, the high-indexfirst layer 1 and the low-index second layer 2 may, be replaced with asingle layer 5 having a so-called “intermediate” refractive index ns,especially one between 1.65 and 1.80, and preferably having an opticalthickness e_(opt.5) of between 50 and 140 nm (preferably from 85 to 120nm). In conventional three-layer antireflection stacks, optimized forperpendicular viewing, this thickness is somewhat above 120 nm. Thisintermediate-index layer has an optical effect similar to that of ahigh-index layer/low-index layer sequence when it forms the firstsequence, i.e. the two layers closest to the substrate bearing thestack. It has the advantage of reducing the overall number of layers inthe stack. It is preferably based on a mixture of, on the one hand,silicon oxide and, on the other hand, at least one metal oxide chosenfrom tin oxide, zinc oxide and titanium oxide. It may also be based onsilicon oxynitride or oxycarbide and/or based on aluminium oxynitride.

The materials most suitable for forming the first and/or the thirdlayer, those having a high index, are based on one or more metal oxideschosen from zinc oxide ZnO, tin oxide SnO₂ and zirconium oxide ZrO₂.They may also be based on one or more nitrides chosen from siliconnitride Si₃N₄ and aluminium nitride AlN.

Using a nitride layer for one or other of the high-index layers,especially the third layer at least, makes it possible to add afunctionality to the stack, namely an ability to better withstand theheat treatments without any appreciable impairment in its opticalproperties. Now, such a functionality is important in the case ofglazing of the windscreen or shop counter type, since the glazing has toundergo high-temperature heat treatments of the bending, toughening,annealing or laminating type, in which the glasses have to be heated toat least 120° C. (for laminating) up to 500 to 700° C. (for bending andtoughening). It then becomes paramount to be able to deposit the thinlayers before the heat treatment without this causing a problem (todeposit layers on bent glass is tricky and expensive, and it is muchsimpler from the industrial standpoint to carry out the depositionbefore any heat treatment).

It is thus possible to have a single configuration of antireflectionstack whether or not the carrier glass is intended to undergo a heattreatment.

Even if it is not intended to be heated, it is still beneficial to useat least one nitride layer as this improves the mechanical and chemicaldurability of the stack in its entirety.

According to one particular embodiment, the first and/or third layer,those having a high index, may in fact be formed from several superposedhigh-index layers. Most particularly, they may form a bilayer of theSnO₂/Si₃N₄ or Si₃N₄/SnO₂ type. This has the following advantage: theSi₃N₄ tends to be deposited a little less easily and a little moreslowly by reactive sputtering than a conventional metal oxide such asSnO₂, ZnO or ZrO₂. Especially for the third layer, which is the thickestand most important for protecting the stack from any damage resultingfrom a heat treatment, it may be beneficial to duplicate the layer so asto just bring the Si₃N₄ thickness sufficient to obtain the effect ofprotection against the desired heat treatments and to optically“supplement” the layer with SnO₂ or ZnO.

The most appropriate materials for forming the second and/or the fourthlayer, those having a low index, are based on silicon oxide, siliconoxynitride and/or oxycarbide or else based on a mixed silicon aluminiumoxide. Such a mixed oxide tends to have better durability, especiallychemical durability, than pure SiO₂ (an example of this is given inpatent EP-791 562). The respective proportions of the two oxides may beadjusted in order to improve the expected durability without excessivelyincreasing the refractive index of the layer.

The glass chosen for the substrate coated with the stack according tothe invention or for the other substrates which are associated with itin order to form a glazing assembly, may in particular be, for example,extra clear of the “Diamant” type or clear of the “Planilux” type ortinted glass of the “Parsol” type, these three products being sold bySaint-Gobain Vitrage, or else may be of the “TSA” or “TSA++” type asdescribed in patent EP 616 883. It may also be an optionally tintedglass as described in patents WO 94/14716, WO 96/00194, EP 0 644 164 orWO 96/28394. It may act as a filter against ultraviolet-type radiation.

The substrate or substrates may have undergone heat treatments, that theantireflection stack according to the invention is capable ofwithstanding, such as annealing, toughening, bending or even folding,that is to say bending with a very small radius of curvature(application in particular for shop counters and windows), mostparticularly when at least the high-index third layer of the stackcontains silicon nitride or aluminium nitride. This means that such heattreatments have no or virtually no effect on the mechanical and chemicaldurability of the stack and do not modify (or only very slightly modify)its optical properties.

The subject of the invention is also glazing incorporating thesubstrates provided with the multilayer stack defined above. The glazingin question may be “monolithic”, that is to say composed of a singlesubstrate coated with the multilayer stack on one of its faces. Itsopposite face may be devoid of any antireflection coating, being bare orcovered with a coating having another functionality. This may be acoating having a solar-protection function (using, for example, one ormore silver layers surrounded by dielectric layers, or layers ofnitrides such as TiN or ZrN or of metal oxides or of steel or of anNi—Cr alloy), having a low-emissivity function (for example one made ofa doped metal oxide, such as F:SnO₂ or tin-doped indium oxide ITO or oneor more silver layers), having an antistatic function (anoxygen-substoichiometric or doped metal oxide), a heating layer (a Cu-or Ag-doped metal oxide, for example) or an array of heating wires(copper wires or bands screen-printed using a conducting silver paste),an antifogging function (using a hydrophilic layer), an anti-rainfunction (using a hydrophobic layer, for example one based on afluoropolymer) or an antifouling function (a photocatalytic coatingcomprising at least partially crystallized TiO₂ in the anatase form).

The said opposite face may also be provided with an antireflection stackto maximize the desired antireflection effect. In this case, this mayalso be an antireflection stack meeting the criteria of the presentinvention or it may be another type (B) of antireflection coating.

One particularly beneficial glazing assembly incorporating a substratecoated according to the invention has a laminated structure, whichconsists of two glass substrates joined together by one or more sheetsof a thermoplastic such as polyvinyl butyral PVB. In this case, one ofthe two substrates is provided, on the external face (the face oppositethat where the glass joins the thermoplastic sheet), with theantireflection stack (A) according to the invention. The other glass,also on its external face, may, as previously, be bare, coated withlayers having another functionality, coated with the same antireflectionstack (A) or with another type (B) of antireflection stack, or else witha coating having another functionality as in the previous case (thisother coating may also be placed not on a face opposite the join but onone of the faces of one of the rigid substrates which points towards theside with the thermoplastic joining sheet). Conventionally, the faces ofthe glazing are numbered starting from the outermost face. Thus, it ispossible to have the antireflection stack according to the invention onthe 1 and/or 4 faces (that is to say on the face of the glass panespointing towards the outside of the glazing, when there are two glasspanes).

It is therefore possible to provide the laminated glazing with an arrayof heating wires, with a heating layer or with a solar-protectioncoating on the “inside” of the laminate (and therefore on the 2 and/or 3faces). Solar-protection coatings based on two silver layers sandwichedbetween three layers or multilayers made of particularly appropriatedielectric material are described in patents EP 638 528, EP 718 250, EP844 219 and EP 847 965.

According to another alternative embodiment, instead of depositing thesolar-protection coating on one of the rigid substrates (one of theglass panes), it is possible to deposit it on a sheet of polymer of thePET (polyethylene terephthalate) type, which is placed between twosheets of thermoplastic polymer of the PVB type before being laminatedwith the two glass panes. This type of configuration is especiallydescribed in patents EP 758 583, U.S. Pat. No. 5,932,329, EP 839 644, WO99/45415 and EP 1 010 677.

An antifouling layer (for example based on photocatalytic TiO₂ asdescribed in patents WO 97/10186, WO 97/10185 or WO 99/44954), or else ahydrophilic or hydrophobic layer may be placed on the “outside” (andtherefore on the 1 or 4 faces, on the face not covered with theantireflection stack according to the invention).

It is thus possible to have configurations of the type:

-   antireflection coating (A)/glass/PVB/bare or anti-fouling,    hydrophilic or hydrophobic functionalized glass;    -   antireflection coating (A)/glass/PVB/glass/antireflection        coating (A) or (B);    -   antireflection coating (A)/glass/PVB/PET provided on one of its        faces with a solar-protection coating/PVB/glass/optional        antireflection coating (A) or (B); antireflection coating        (A)/glass/PVB/solar-protection coating/glass/optional        antireflection coating (A) or (B);    -   antireflection coating (A)/glass/solar-protection        coating/PVB/glass/optional antireflection coating (A) or (B).

These configurations, especially with both substrates bent and/ortoughened, make it possible to obtain motor-vehicle glazing, andespecially a highly advantageous windscreen since the standards impose,on motor vehicles, windscreens with a high light transmission, of atleast 75% at normal incidence according to the European standards. Byincorporating antireflection coatings in the usual windscreen laminatedstructure, the light transmission of the glazing is increased, forexample by at least 6%, this being advantageous as it allows more lightinto the passenger compartment of the vehicle, providing better comfortand safety. In another use, the reduction in light reflection may serveto reduce the energy transmission while still complying with thestandards in terms of light transmission. Thus, it is possible toincrease the solar-protection effect of the windscreen, for example byabsorption in the glass substrates, using glass substrates that aretinted more strongly. Specifically, it is thus possible to make thelight reflection value of a standard laminated windscreen go from 13.6%to less than 6.5%, while still reducing its energy transmission by atleast 7%, taking it for example from 48.5% to 41.5%, with a constantlight transmission of 75%.

Various objectives may be achieved by choosing another antireflectioncoating, of the (B) type, for the other face of the glazing (whetherthis is monolithic or laminated). It may be desirable for the secondcoating to be even simpler to manufacture and for it therefore to have asmaller number of layers. It may also be beneficial to differentiate therequired level of durability for the two coatings according to theirdegree of exposure to mechanical or chemical assault. Thus, for glazingfitted into a vehicle, it may be judicious to provide the external faceof the glazing with a more durable coating, even if optically it is lessefficient, than the inner face turned towards the passenger compartment(the reader need only think, for example, of the repeated mechanicalassault by the windscreen wiper blades).

The invention also includes glazing provided with the antireflectionstack of the invention and in the form of multiple glazing, that is tosay using at least two substrates separated by an intermediategas-filled cavity (double or triple glazing). Here again, the otherfaces of the glazing may also be antireflection-treated or may haveanother functionality.

It should be noted that this other functionality may also consist inplacing, on the same face, the antireflection stack and the stack havinganother functionality (for example by surmounting the antireflectioncoating with a very thin antifouling coating layer).

Greater durability may be obtained by reducing the number of layers, oreven keeping only one of them, in order to minimize the internalstresses in the stack and the risks of delamination, and/or by tailoringthe process of depositing the layers. It is known that hot deposition,using pyrolysis techniques for example, make it possible to obtainlayers that are more adherent and stronger than those deposited cold,for example by sputtering.

This type-B antireflection coating may be chosen from one of thefollowing coatings:

-   -   a single low-index layer, having a refractive index of less than        1.60 or 1.50, especially about 1.35 to 1.48. It is preferably an        SiO₂ layer having a thickness of between 80 and 120 nm, which        may be deposited by sol-gel, CVD, corona discharge or        sputtering;    -   again only a single layer, but one whose refractive index varies        through its thickness in order to improve the performance        thereof. It may especially be a layer based on silicon        oxynitride SiO_(x)N_(y), where x and y vary through its        thickness, or based on a mixed silicon titanium oxide        Si_(z)Ti_(i-z)O₂, where z varies through the thickness of the        layer. This type of coating may be deposited by plasma CVD and        is explained in detail in patent FR 98/16118 of 21 Dec. 1998;    -   a two-layer stack comprising, in succession, a layer having a        high index of at least 1.8 (especially made of tin oxide SnO₂,        zinc oxide ZnO, zirconium oxide ZrO₂, titanium oxide TiO₂,        silicon nitride Si₃N₄ and/or aluminium nitride AlN) and then a        layer having a low index of less than 1.65, especially made of        silicon oxide, oxynitride or oxycarbide;    -   a three-layer stack comprising, in succession, a layer of medium        index between 1.65 and 1.80, of the silicon oxycarbide or        oxynitride and/or aluminium oxycarbide or oxynitride type, a        layer having an index equal to or greater than 1.9, such as        Sno₂, ZnO, ZrO₂, Si₃N₄ or TiO₂, and again a layer having a low        index of less than 1.65, made of SiO₂ or a mixed silicon        aluminium oxide (possibly fluorinated according to the        aforementioned patent EP-791 562), as may be all the other mixed        Si—Al oxide layers mentioned above).

The subject of the invention is also the process for manufacturing theglass substrates with an antireflection coating (A) according to theinvention. A process consists in depositing all the layers, insuccession, one after the other, by a vacuum technique, especially bymagnetic-field-enhanced sputtering or by corona discharge. Thus, it ispossible to deposit the oxide layers by reactive sputtering of the metalin question in the presence of oxygen and the nitride layers in thepresence of nitrogen. To make SiO₂ or Si₃N₄, the process can start witha silicon target which is lightly doped with a metal such as aluminiumin order to make it sufficiently conducting.

In the case of the optional antireflection coating B of another type,several deposition techniques are possible, those involving a heattreatment or those carried out cold, especially the sol-gel technique,pyrolysis techniques carried out in the pulverulent, solid or vapourphase, the latter also being known by the name CVD (Chemical VapourDeposition). The CVD may be plasma-enhanced CVD. It is also possible touse vacuum techniques of the sputtering type.

The antireflection coating A may also be deposited hot. Preferably, thecoating A is deposited by sputtering and the coating B by pyrolysis ofthe CVD type. It is also possible, as recommended by the aforementionedpatent WO 97/43224, for some of the layers of one or other of the stacksto be deposited by a hot deposition technique of the CVD type, the restof the stack being deposited cold by sputtering.

The subject of the invention is also applications of such glazing, mostof which have already been mentioned: shop windows, display cabinets andcounters, glazing for buildings, glazing for any land-, air- orsea-going vehicle, especially the windscreen of a vehicle, the rearwindow, sunroof, side windows or antidazzle screens, for any displaydevice such as computer screens, televisions, any glass furniture or anydecorative glass. Such glazing may be bent/toughened after the layershave been deposited.

The details and advantageous characteristics of the invention will nowbe apparent from the following non-limiting examples, with the aid ofthe figures:

FIG. 1: a substrate provided with a four-layer antireflection stack Aaccording to the invention;

FIG. 2: monolithic glazing provided with two antireflection stacks (A,A) or (A, B);

FIG. 3: laminated glazing provided with two antireflection stacks (A, A)or (A, B).

FIG. 1, which is highly schematic, shows in cross section a glass pane 6surmounted by a four-layer antireflection stack (A).

FIG. 2, also highly schematic, shows monolithic glazing in crosssection, with a glass pane (6) provided on each of its faces with anantireflection stack.

FIG. 3 shows laminated glazing in cross section, each of the externalfaces of which is antireflection-treated.

Examples 1 to 10 below are modelling results and Examples 11 to 15 wereactually produced. All Examples 1 to 13 relate to four-layerantireflection stacks, while Example 14 relates to a three-layerantireflection coating. The layers were all deposited conventionally byreactive magnetic-field-enhanced sputtering in an oxidizing atmosphereusing an Si or metal target to make the SiO₂ or metal oxide layers,using an Si or metal target in a nitriding atmosphere to make thenitrides and in a mixed oxidizing/nitriding atmosphere to make theoxynitrides. The Si targets may contain a small amount of another metal,especially Zr, Al, especially so as to make them more conducting.

EXAMPLES 1 to 10

For Examples 2-4 and 7 to 10 a, the antireflection stack used was thefollowing:

(6): Glass (1): SnO₂ index n₁ = 2 (2): SiO₂ index n₂ = 1.46 (3): SnO₂(or Si₃N₄) index n₃ = 2 (4): SiO₂ index n₄ = 1.46.

For Comparative Examples 5-6, the antireflection stack used was thefollowing:

(6): Glass (1): SnO₂ index = 2 (2): SiO₂ index = 1.46 (3): TiO₂ index =2.40 (4): SiO₂ index = 1.46.

Examples 1 to 7 relate to monolithic glazing and Examples 8 to 10arelate to laminated glazing.

Example 1 (Comparative)

This is the glass pane 6 in FIG. 1, but without any coating. The glassis a clear silica-soda-lime glass 2 mm in thickness, sold under the namePlanilux by Saint-Gobain Vitrage.

Example 2

This is the glass pane 6 in FIG. 1 provided on only one face with theantireflection stack.

The table below gives the index n₁ and the geometrical thickness e_(i)in nanometers for each of the layers:

EXAMPLE 2 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.01.46 e_(i) 15 nm 35 nm 90 nm 105 nm

The purpose of this example is to minimize as far as possible the R_(L)value of the glass pane 6 (on the coated side) at an angle of incidenceof 60°.

Example 3

This is the same glazing configuration as in Example 2, but the purposebeing both to reduce the R_(L) value on the side where the layers areand to obtain a colour in the blue-greens (negative a* and b*) inreflection, again at 60° incidence. The thicknesses have been adjusteddifferently:

EXAMPLE 3 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.01.46 e_(i) 19 nm 17 nm 100 nm 95 nm

Example 4

Again we have the configuration of Examples 2 and 3, but here themotivation is to obtain the best possible compromise between the maximumreduction in R_(L) at oblique incidence (60°) and the reduction in R_(L)at normal incidence (0°):

Example 4

EXAMPLE 4 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.01.46 e_(i) 20 nm 35 nm 80 nm 105 nm

Comparative Example 5

This example uses a layer 3 (TiO₂) having a significantly higher indexthan that recommended in the invention. The optical thickness of thislayer 3 is chosen to be identical to that of the layer 3 of Example 2.

EXAMPLE 5 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.401.46 e_(i) 15 nm 35 nm 75 nm 105 nm

Comparative Example 6

This example repeats the same sequence of layers as in ComparativeExample 5, with the objective of minimizing the R_(L) value on themultilayer side at oblique incidence (60°).

EXAMPLE 6 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.401.46 e_(i) 25 nm 35 nm 110 nm 105 nm

Example 7

This example has the configuration of FIG. 2, namely a glass pane (6)coated on both its faces with the same antireflection stack A. The glasspane (6) is again made of clear Planilux glass 2 mm in thickness.

The objective here is to obtain a good compromise between reducing R_(L)and obtaining an attractive colour in reflection, again at 60°.

EXAMPLE 7 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.01.46 e_(i) 19 nm 17 nm 100 nm 95 nm

Comparative Example 8

This is laminated glazing as shown in FIG. 3, but without anyantireflection coating.

Its structure is as follows:

-   -   →glass pane 6: glass bulk-tinted in the greens, having the        reference TSA³⁺ from Saint-Gobain Vitrage, and having the        characteristics described in Patent EP 0 644 164 (the        composition is very similar to that described in the last        example of the said patent, but with a total iron content        expressed in the form of Fe₂O₃ which is only 0.92% by weight)        and a thickness of 2.1 mm;    -   sheet 7: 0.7 mm PVB sheet;    -   glass pane 6′: clear Planilux glass 1.6 mm in thickness.

Example 9

This is the laminated glazing in FIG. 3, with the structure described inComparative Example 8 and on the 4 face (conventionally, the faces ofthe glass panes making up glazing are numbered in ascending orderincreasing from the outside to the inside of the passenger compartmentor the building in which the glazing is to be fitted), only a singleantireflection stack according to the invention, the characteristics ofwhich are given below: the objective here is to achieve the bestcompromise between reducing R_(L) and obtaining a satisfactory colour inreflection on the “layers side” at oblique incidence (60°):

EXAMPLE 9 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) 2.0 1.46 2.01.46 e_(i) 19 nm 17 nm 100 nm 95 nm

Example 9a

This is the same glazing as in Example 9, except that here the glasspane 6 is thicker, having a thickness of 3.3 mm, so as to achieve agreater filtering effect with respect to solar radiation.

Example 10

This is the laminated structure shown in FIG. 3 and Example 8, with, onthe 4 face, the stack A according to Example 9 and, on the 1 face, anantireflection coating 3 different from A and consisting of a layer ofSiO_(x)N_(y) whose refractive index decreases through its thickness inaccordance with the teaching of the aforementioned patent FR98/16118 andwhich may be deposited by plasma CVD. Its thickness is about 260 nm.

Example 10a

This is the same glazing as in Example 9, except that here the glasspane 6 is thicker, having a thickness of 4.00 mm, in order to achieve agreater filtering effect with respect to solar radiation.

EXAMPLES 11 to 13

All these examples were actually produced on clear glass panes 6 of thePlanilux type with a thickness of 2 mm in the case of Examples 11 and 12and a thickness of 4 mm in the case of Example 13.

Example 11

The glass pane in accordance with FIG. 1 was coated, on one of its facesonly, with the following antireflection stack according to theinvention:

-   -   Glass(⁶)/SnO₂ ⁽¹⁾/SiO₂ ⁽²⁾/SnO₂ ⁽³⁾/SiO₂ ⁽⁴⁾

EXAMPLE 11 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) ≈2.05 ≈1.46≈2.05 ≈1.46 e_(i) 19 nm 17 nm 100 nm 95 nm

The SiO₂ layers contain in fact about 10% by weight of aluminium oxideso as to give them better durability, especially chemical durability.

The aim of this example is to lower the R_(L) at 600 and to obtainnegative values of a* and b* in reflection and for these to be, inabsolute values, not very high in oblique reflection (again on thelayers side).

Example 12

Compared with Example 11, the two SnO₂ layers have been substituted withtwo Si₃N₄ layers.

The sequence is therefore the following:

-   -   Glass ⁽⁶⁾/Si₃N₄ ⁽¹⁾/SiO₂ ⁽²⁾/Si₃N₄ ⁽³⁾/Sio₂ ⁽⁴⁾

EXAMPLE 12 LAYER (1) LAYER (2) LAYER (3) LAYER (4) n_(i) ≈2.08 ≈1.46≈2.08 ≈1.46 e_(i) 19 nm 17 nm 100 nm 95 nm

The SiO₂ layers also contain about 10% aluminium oxide by weight.

Substituting Si₃N₄ for SnO₂ makes it possible for the stack to bebendable/toughenable. This means, within the context of the invention,that when the coated substrate undergoes a heat treatment of this type,its optical properties remain almost unchanged. Quantitatively, it maybe estimated that there is no significant optical change in reflectionwhen the value of ΔE=(ΔL*²+Δa*²+Δb*2), which measures the variations inL*, a* and b* before and after heat treatment, remains less than 2.5 orbetter still, less than 2.

Example 13

The glazing according to this example is treated on both its faces. Itis provided both on the 1 face and on the 2 face with the same stack,that used in Example 11 (alternatively, one or both of the SnO₂ layersmay be replaced with Si₃N₄).

The table below gives for all the examples of the present patent thefollowing photometric values:

-   -   R_(L)(60°): the light reflection on the “layers side” at 60°with        respect to the normal to the glazing, under illuminant D₆₅, in        %;    -   a*(60°), b*(60°): the dimensionless calorimetric values of        R_(L)(60°);    -   R_(L)(0°): the light reflection on the “layers side” at normal        incidence, in %;    -   a*(0°), b*(0°): the dimensionless calorimetric values of R_(L)        at normal incidence;    -   T_(L)(0°): the light transmission under illuminant D₆₅, in %.

R_(L) R_(L) T_(L) EXAMPLE (60°) a* (60°) b* (60°) (0°) a* (0°) b* (0°)(0°) 1 15.4 −0.3 −0.3 8.0 −0.2 −0.5 90.8 2 11.8 2.2 −4.5 5.8 3.5 −19.392.9 3 12.1 −1.0 −1.9 5.3 −2.2 −2.6 93.5 4 11.9 1.8 −1.9 5.0 9.8 −23.593.8 5 13.8 5.4 −4.3 9.1 1.2 −17.3 89.7 6 11.8 2.1 −4.8 6.2 −5.6 −6.692.5 7 7.9 −2.9 −6.3 2.5 −7.0 −7.0 96.3 8 13.7 −2.9 0.4 7.2 −2.8 0.078.7 9 10.0 −5.6 −1.2 4.5 −6.1 −1.9 80.7  9a 9.1 −6.8 −1.6 4.0 −7.3 −2.075.0 10  7.3 −3.3 −2.9 1.8 −5.6 −6.0 83.4 10a 6.5 −4.8 −3.2 1.7 −6.2−5.7 75.0 11  11.8 −0.7 −0.8 5.3 −3.4 −0.4 92.3 12  11.6 −0.6 −0.9 5.2−3.7 −7.1 94.0 13  7.7 −0.6 −2.1 2.3 −3.7 −7.1 95.3

Examples 11 and 12 underwent a mechanical durability test, the TABERtest consisting in subjecting the substrate on its face coated with thelayers to a circular rubbing action by abrasive grinding mills with aload of 500 grams. After 650 revolutions, the observed difference inhaze AH was 1.6 in the case of Example 12 and only 0.5 in the case ofExample 13.

This confirms that the stacks according to the invention, even whendeposited by sputtering, have a satisfactory durability which is furtherenhanced if preference is given to Si₃N₄ rather than to SnO₂ for makingall or some of the high-index layers.

From the summarizing table of the photometric for all of the examples,it is possible to make following comments:

-   -   once the refracted indices have been selected, the geometrical        thicknesses of the layers may be adjusted according to whether        the R_(L) or the colorimetric response is emphasized: comparing        Examples 2 and 3, it may be seen that the R_(L) at 60° may go        below the 12% level, but with a positive a*(Example 2), for a        clear glass substrate coated especially on only one face, or        else to have a slightly higher R_(L) value but offset by being        certain of having a* and b* values at 60° which are more        negative;    -   Example 4 allows both the R_(L) at 60° to go below the 12% level        and the R_(L) at 0° to reach 5%. This may be beneficial when the        application is for glass of the counter type, which is liable to        be observed at very varied angles of incidence.

According to the invention, R_(L) at oblique incidence may go below 8%if the glass is provided with antireflection stacks on both its faces(Example 7);

-   -   Comparative Examples 5 and 6 show the advantage of using SnO₂ or        Si₃N₄ rather than TiO₂ as the high-index layer: Example 5 tries        to reproduce, in optical thickness, Example 2 (the optical        thickness of layer 3 is 180 nm in both cases), but the result is        less good: the R_(L) at 60° is 13.8%. Example 6 shows that        better R_(L) values at 60° may be achieved, but at the expense        of greatly thickening the layer 3 (optical thickness of 264 nm),        which is not satisfactory in terms of production efficiency;    -   The examples of laminated glazing confirm the benefit of        providing car windscreens with antireflection coatings according        to the invention;    -   A reduction of more than 6% in R_(L) at 60° is achieved for a        windscreen treated on both faces with the stack of the invention        deposited on the 4 face (Example 10) as compared with a standard        windscreen (Example 8). This therefore makes it possible either        to increase the level of light transmission or to use darker or        thicker glass, and therefore to provide better heat protection        for the passengers in the vehicle, while still exceeding the 75%        level for TL; this is shown by Examples 10 and 10a on the one        hand, and Examples 9 and 9a on the other;    -   Examples 11 to 13 confirm the modelled results: as compared with        the bare glass of Example 1, the R_(L) at 60° is thus reduced by        at least 3%, almost 4%, while managing to keep the corresponding        a* and b* values negative and, in absolute value, at most 2.1        (and even at most 1 in absolute value in the case of a*). The        effect is even more pronounced if the glass is treated on both        its faces, when there is a drop of more than 7% in the R_(L) at        60°. Furthermore, in all cases, there is also an appreciable        reduction in the R_(L) at normal incidence (about 3% per treated        face), again with negative a* and b* values: a person viewing        the glazing over a wide range of angles of incidence will        therefore see glazing which reflects little and does not        “switch” from one colour to the other in reflection depending on        the way in which he looks at it, this being highly advantageous.

Example 14

This example relates to a stack according to the invention having onlythree layers, the first two layers 1, 2 being replaced with a singlelayer 5, as shown in FIG. 1.

The substrate is a clear Planilux glass 2 mm in thickness, treated ononly one of its faces. The stack is as follows:

-   -   Glass/60 nm SiO_(x)N_(y)(n=1.70)/100 nm Si₃N₄/95 nm, SiO₂.

The photometric data of the coated glass are as follows:

-   -   R_(L)(60°)=12.1% a*=−0.3 b*=−1.2;    -   R_(L)(0°)=5.3% a*=−2.9 b*=−5.0;    -   T_(L)(0°)=93.5%.

It is thus possible to achieve with three layers similar performance tothat of a four-layer antireflection stack according to the invention:the calorimetric response in reflection at 600 and 0° is satisfactory.The durability, especially mechanical durability, of the three-layerstack is moreover at least equivalent, if not better, than that of thefour-layer stack of the invention using at least one Si₃N₄ layer.

Example 15

This example relates to laminated glazing with the (Si₃N₄SiO₂/Si₃N₄/SiO₂) antireflection stack according to the invention on the4 face and, between the two joining PVB sheets, a PET sheetfunctionalized by the (indium oxide/Ag/indium oxide/Ag/indium oxide)solar-protection coating.

The sequence is as follows:

-   -   Planilux glass (2.1 mm)/PVB (380 microns)/PET (160        microns)/In₂O₃ (20 nm)/Ag (7 nm)/In₂O₃ (60 nm)/Ag (7 nm)/In₂O₃        (20 nm)/PVB (380 microns)/Planilux glass (2.1 mm)/Si₃N₄ (17        nm)/SiO₂ (18 nm)/Si₃N₄ (104 nm)/SiO₂ (108 nm).

The value of the light reflection at 60°, RL (600), is 11.2%, whereas itis 14.9% if it is measured on laminated glazing which is identical butdoes not have the antireflection coating on the 4 face.

The value of T_(L) at 0° is 75.1% (it is 75.3% without theantireflection coating).

The value of the energy reflection at 0° (normal incidence), RE (0°), is25.6% and the energy transmission value at 0°, T_(E) (0°), is 52.2%.

This example shows the effectiveness of a solar-protection coating whichsignificantly reflects the infrared. However, against this, the use ofsuch a coating tends to increase the light reflection on the interiorside. The antireflection stack according to the invention makes itpossible to compensate for this increase in reflection and to maintainthe level of reflection (on the inside) that the laminated glazing wouldhave without the solar-protection coating.

The same solar-protection effect is obtained if a coating comprising twosilver layers, deposited directly on one of the glass panes, with asingle intermediate PVB sheet, is used.

1. A manufactured article, comprising: a transparent substrate; anantireflection coating on at least one face of the transparentsubstrate, said antireflection coating made of a stack of thin layers ofdielectric material having alternately high and low refractive indices,wherein the stack comprises, in succession: a high-index first layer,having a refractive index n₁ of between 1.8 and 2.2 and a geometricalthickness e₁ of between 5 and 50 nm; a low-index second layer, having arefractive index n₂ of between 1.35 and 1.65 and a geometrical thicknesse₂ of between 5 and 50 nm; a high-index third layer, having a refractiveindex n₃ of between 1.8 and 2.2 and a geometrical thickness e₃ ofbetween 70 and 120 nm; a low-index fourth layer, having a refractiveindex n₄ of between 1.35 and 1.65 and a geometrical thickness e₄ of atleast 80 μm, wherein the antireflection stack uses, at least for itshigh-index third layer, silicon nitride or aluminium nitride to undergoa heat treatment of bending, toughening, or annealing.
 2. Themanufactured article according to claim 1, wherein n₁ and/or n₃ arebetween 1.85 and 2.15.
 3. The manufactured article according to claim 1,wherein n₂ and/or n₄ are between 1.35 and 1.55.
 4. The manufacturedarticle according to claim 1, wherein e₁ is between 10 and 30 nm.
 5. Themanufactured article according to claim 1, wherein e₂ is between 10 and35 nm.
 6. The manufactured article according to claim 1, wherein e₃ isbetween 70 and 75 Nm.
 7. The manufactured article according to claim 1,wherein e₄ is greater than or equal to 80 nm and less than or equal 120nm.
 8. The manufactured article according to claim 1, wherein thehigh-index first layer and/or the high-index third layer are based onone or more metal oxides chosen from zinc oxide, tin oxide, andzirconium oxide, or based on one or more nitrides chosen from siliconnitride and aluminium nitride.
 9. The manufactured article according toclaim 1, wherein the high-index first layer and/or the high-index thirdlayer include a superposition of several high-index layers.
 10. Themanufactured article according to claim 1, wherein the low-index secondlayer and/or the low-index fourth layer are based on at least one of asilicon oxide, silicon oxynitride and/or oxycarbide, or on a mixedsilicon aluminium oxide.
 11. The manufactured article according to claim1, wherein the substrate is made of clear or bulk-tinted glass.
 12. Themanufactured article according to claim 1, wherein light reflection on aside where the stack of thin layers is provided is reduced by a minimumvalue of 3 or 4% at an angle of incidence of between 50 and 70 degrees.13. The manufactured article according to claim 1, wherein acalorimetric response of light reflection on a side where the stack ofthin layers is provided is such that corresponding a* and b* values inthe (L*, a*, b*) colorimetry system are negative at an angle ofincidence of between 50 and 70 degrees.
 14. A glazing including themanufactured article according to claim 1, wherein the glazing comprisesthe transparent substrate provided, on a second face opposed to the atleast one face either with no antireflection stack or with a multilayerantireflection stack, or with another type of antireflection coating, orwith a coating having another functionality of solar-protection,low-emissivity, antifouling, antifogging, anti-rain, or heating.
 15. Aglazing including the manufactured article according to claim 1,comprising: a laminated structure in which the transparent substrate anda second transparent substrate are joined together using a sheet ofthermoplastic, the second transparent substrate being provided, on theopposite side to the sheet of thermoplastic, either with noantireflection coating, or also with an antireflection stack, or withanother type of antireflection coating, or with a coating having anotherfunctionality of the solar-protection, low-emissivity, antifouling,antifogging, anti-rain, or heating, the coating having anotherfunctionality possibly also being on one of the faces of the substrateswhich are turned towards the thermoplastic joining sheet.
 16. A glazingincluding the manufactured article according to claim 1, furthercomprising: a laminated structure with one or more sheets of joiningpolymer, wherein the antireflection coating is disposed on at least oneof the faces on the opposite side to the one or more sheets of joiningpolymer, and a solar-protection-coating is in contact with the one ormore sheets of joining polymer.
 17. A glazing including the manufacturedarticle according to claim 14, wherein the another type ofantireflection coating is present and includes one of the followingcoatings: a single low-index layer, having an index of less than 1.60; asingle layer whose refractive index varies through its thickness,including silicon oxynitride SiO_(x)N_(y), where x and y vary throughits thickness; a two-layer stack, comprising, in succession, a layerhaving a high index of at least 1.8 including at least one of tin oxide,zinc oxide, zirconium oxide, titanium oxide, silicon nitride oraluminium nitride, and then a layer having a low index, of less than1.65, including at least one of silicon oxide, oxynitride, oroxycarbide; a three-layer stack comprising, in succession, a layerhaving a medium index of between 1.65 and 1.8 including siliconoxycarbide or oxynitride and/or aluminium oxycarbide or oxynitride, alayer having a high index of greater than 1.9 including SnO₂ or TiO₂,and a layer having a low index of less than 1.65, including mixed Si—Aloxide or silicon oxide.
 18. A method of making the glazing according toclaim 14, including the steps of depositing the antireflection stack orstacks by sputtering and depositing the optional antireflection coatingby a sol-gel technique, by a pyrolysis technique of CVD or plasma CVD,by sputtering, or by corona discharge.
 19. A method of using the glazingaccording to claim 14 including using the glazing as an interior orexterior glazing for buildings, as a planar or curved shop displaycabinet or counter glazing, as a glazing for a vehicle side window, as aglazing for a vehicle rear window, as a glazing for a vehicle sunroof,as a glazing for a vehicle windscreen, as a glazing for protecting apainting, as a glazing for an antidazzle computer screen, or as aglazing for glass furniture.
 20. A manufactured article comprising: atransparent substrate; an antireflection coating on at least one face ofthe transparent substrate having a stack of thin layers of dielectricmaterial, wherein the stack comprises, in succession: a high-index firstlayer, having a refractive index n₁ of between 1.8 and 2.2 and ageometrical thickness e₁ of between 5 and 50 nm; a low-index secondlayer having a refractive index n₂ of between 1.35 and 1.65 and ageometrical thickness e₂ of between 5 and 50 rim; a high-index thirdlayer having a refractive index n₃ of between 1.8 and 2.2 and ageometrical thickness e₃ of between 70 and 120 nm; a low-index fourthlayer having a refractive index n₄ of between 1.35 and 1.65 and ageometrical thickness e₄ of at least 80 nm, wherein the stack isconfigured to reduce light reflection by at least 3% at an angle ofincidence of between 50 and 70 degrees, and wherein the stack isconfigured to produce a colorimetric response of light reflection on aside where the stack of thin layers is provided such that correspondinga* and b* values in the (L*, a*, b*) colorimetry system are negative atan angle of incidence of between 50 and 70 degrees.
 21. The manufacturedarticle according to claim 20, wherein n₁ and/or n₃ are between 1.85 and2.15.
 22. The manufactured article according to claim 20, wherein n₂and/or n₄ are between 1.35 and 1.55.
 23. The manufactured articleaccording to claim 20, wherein e₁ is between 10 and 30 nm.
 24. Themanufactured article according to claim 20, wherein e₂ is between 10 and35 nm.
 25. The manufactured article according to claim 20, wherein e₃ isbetween 70 and 75 nm.
 26. The manufactured article according to claim20, wherein e₄ is greater than or equal to 80 nm and less than or equalto 120 nm.
 27. The manufactured article according to claim 20, whereinthe high-index first layer and/or the high-index third layer are basedon one or more metal oxides chosen from zinc oxide, tin oxide, andzirconium oxide, or based on one or more nitrides chosen from siliconnitride and aluminium nitride.
 28. The manufactured article according toclaim 20, wherein the high-index first layer and/or the high-index thirdlayer include a superposition of several high-index layers.
 29. Themanufactured article according to claim 20, wherein the low-index secondlayer and/or the low-index fourth layer are based on silicon oxide,silicon oxynitride and/or oxycarbide, or on a mixed silicon aluminiumoxide.
 30. The manufactured article according to claim 20, wherein thesubstrate is made of clear or bulk-tinted glass.
 31. A glazing includingthe manufactured article according to claim 20, wherein the glazingcomprises the transparent substrate provided on a second face opposed tothe at least one face either with no antireflection stack or with amultilayer antireflection stack, or with another type of antireflectioncoating, or with a coating having another functionality ofsolar-protection, low-emissivity, antifouling, antifogging, anti-rain,or heating.
 32. A glazing including the manufactured article accordingto claim 20, comprising: a laminated structure in which the transparentsubstrate and a second transparent substrate are joined together using asheet of thermoplastic, the second transparent substrate being providedon the opposite side to the sheet of thermoplastic, either with noantireflection coating, or also with an antireflection stack, or withanother type of antireflection coating, or with a coating having anotherfunctionality of the solar-protection, low-emissivity, antifouling,antifogging, anti-rain, or heating, the coating having anotherfunctionality possibly also being on one of the faces of the substrateswhich are turned towards the thermoplastic joining sheet.
 33. A glazingincluding the manufactured article according to claim 20, furthercomprising: a laminated structure with one or more sheets of Joiningpolymer, wherein the antireflection coating is disposed on at least oneof the faces on the opposite side to the one or more sheets of joiningpolymer, and a solar-protection-coating is in contact with the one ormore sheets of joining polymer.
 34. A glazing including the manufacturedarticle according to claim 31, wherein the another type ofantireflection coating is present and includes one of the followingcoatings: a single low-index layer, having an index of less than 1.60; asingle layer whose refractive index varies through its thickness,silicon oxynitride SiO_(x)N_(y), where x and y vary through itsthickness; a two-layer stack, comprising, in succession, a layer havinga high index of at least 1.8 including at least one of tin oxide, zincoxide, zirconium oxide, titanium oxide, silicon nitride or aluminiumnitride, and then a layer having a low index, of less than 1.65,including at least one of silicon oxide, oxynitride, or oxycarbide; athree-layer stack comprising, in succession, a layer having a mediumindex of between 1.65 and 1.8 including silicon oxycarbide or oxynitrideand/or aluminium oxycarbide or oxynitride, a layer having a high indexof greater than 1.9 including SnO₂ or TiO₂, and a layer having a lowindex of less than 1.65, including mixed Si—Al oxide or silicon oxide.35. A method of making the glazing according to claim 31; including thesteps of depositing the antireflection stack or stacks by sputtering anddepositing the optional antireflection coating by a sol-gel technique,by a pyrolysis technique of CVD or plasma CVD, by sputtering, or bycorona discharge.
 36. A method of using the glazing according to claim31 including using the glazing as an interior or exterior glazing forbuildings, as a planar or curved shop display cabinet or counterglazing, as a glazing for a vehicle side window, as a glazing for avehicle rear window, as a glazing for a vehicle sunroof, as a glazingfor a vehicle windscreen, as a glazing for protecting a painting, as aglazing for an antidazzle computer screen, or as a glazing for glassfurniture.
 37. A manufactured article, comprising: a transparentsubstrate; an antireflection coating on at least one face of thetransparent substrate, said antireflection coating made of a stack ofthin layers of dielectric material having alternately high and lowrefractive indices, wherein the stack comprises, in succession: ahigh-index first layer, having a refractive index n₁ of between 1.8 and2.2 and a geometrical thickness e₂ of between 5 and 50 nm; a low-indexsecond layer, having a refractive index n₂ of between 1.35 and 1.65 anda geometrical thickness e₂ of between 5 and 50 nm; a high-index thirdlayer, having a refractive index n₃ of between 1.8 and 2.2 and ageometrical thickness e₃ of between 70 and 120 nm; a low-index fourthlayer, having a refractive index n₄ of between 1.35 and 1.65 and ageometrical thickness e₄ of at least 80 nm, wherein the antireflectionstack uses silicon nitride or aluminium nitride for at least one of thehigh-index layers to undergo a heat treatment of bending, toughening, orannealing.